feat: implement integer to Roman numeral conversion (C++)

algorithms/12-integer-to-roman/IntegerToRoman.cpp

@@ -0,0 +1,47 @@
+/**
+ * Solution class for converting an integer to a Roman numeral.
+ */
+
+#include <string>
+#include <vector>
+#include <map>
+
+class Solution {
+ public:
+  string intToRoman(int num) {
+    string roman_str;
+    vector<int> potencies = {1000, 100, 10, 1};
+    map<int, string> roman_equivalences = {
+        {1, "I"},
+        {5, "V"},
+        {10, "X"},
+        {50, "L"},
+        {100, "C"},
+        {500, "D"},
+        {1000, "M"}
+    };
+
+    for (int power : potencies) {
+      int digit = num / power;
+      int power_digit = digit * power;
+      num = num % power;
+
+      if (digit == 0) continue;
+      if (roman_equivalences.count(power_digit)) {
+        roman_str += roman_equivalences[power_digit];
+        continue;
+      }
+      if (digit == 4 || digit == 9) {
+        string prefix = roman_equivalences[power];
+        roman_str += prefix + roman_equivalences[power * (digit + 1)];
+        continue;
+      }
+      if (digit > 5) {
+        roman_str += roman_equivalences[power * 5];
+        digit -= 5;
+      }
+      roman_str += string(digit, roman_equivalences[power][0]);
+    }
+    return roman_str;
+  }
+};